Lily, after deciding to leave Mrs. Hatch, moves into a boarding house by herself, and takes a job as a milliner (a maker of women's hats). She now finds herself officially divorced from society and a regular member of the working class.
Lily, however, has trouble at work when her co-workers ostracize her as a member of the upper-class who has fallen from her high position. Lily is so worried about her situation that she begins taking sleeping medication (described as "her only hope of renewal") to help her rest at night, although the medicine she buys is particularly strong and should not be consumed in large doses. On her way home one day, she falls into a complete daze, in which she meets Rosedale once again. He walks her home, and after a pleasant conversation together, she tells him that she'd be glad if he were to visit often. Her relationship with Rosedale has finally become friendly.
However, all is not well. In April, Lily is fired from her job for poor performance and attendance. Rosedale visits her again, and she admits to him that she has joined the working class with little hope of social uplift. Rosedale desperately wants to help her, but she refuses his offer of money. Wandering aimlessly around town, Lily feels totally hopeless, until she formulates a plan. She goes home to get the collection of letters from her desk, then goes to visit Selden. She apologizes to him for her rude behavior at Mrs. Hatch's house, then tells him that she has left the Emporium. Although she tries to control herself, Lily breaks down into tears in front of Selden, who comforts her. She cryptically tells him that they will not see each other for a long time, and she thanks him for always supporting her in her times of trouble. She confesses that she has passed up too many opportunities in life, and she professes that "life is difficult." Selden tells her she must tell him what her plans are, but Lily says nothing. They know that they love one another, and Lily tells Selden that the "old Lily" will forever be with him. She then subtly drops the package of Bertha's letters into Selden's fire and bids him goodbye.
By this point, the novel is beginning to wind down toward its end. Wharton begins to build capstones on some of her major themes and motifs. She continues her ironic symbolism with the bottle of sleeping medicine; although the bottle is designed to help Lily, it ends up being the thing that kills her.
Toward the end of the novel, some Darwinian themes appear once again. In Chapter 11, Lily thinks of herself as a highly specialized creature designed for life among the upper classes. Her job among the working classes removes her from what she perceives to be her biological element; she uses the theories of Darwin to account for her own instincts and behavior.
At this point in the novel, we begin to see more clearly the parallel structure of the narrative. Lily, at the end of Chapter 11, thinks back to where she was two years ago, at the beginning of the novel. It is important to notice how many events from Book One have corresponding events in Book Two. For instance, the novel opens with an interaction between her and Selden; it ends the same way. Book One shows how Lily succeeds in society despite her increasing debt; Book Two shows her fall from society because of her increasing debt. Luck factors prominently into both books as well. In the first, it leads Lily to lose extensive amounts of money at cards; and in the second, bad luck causes her expulsion from society when she happens to be seen in the wrong place at the wrong time with the wrong man.